Hodierna's Deep Sky Observations

[Image of Hodierna] Longly forgotten and rediscovered only in the early 1980s (published by Serio, Indorato, and Nastasi in the Journal of the History of Astronomy, No. 45 (February 1985) and Kenneth Glyn Jones in Journal of the History of Astronomy, No. 50 (August 1986)), Giovanni Batista Hodierna (1597-1660), astronomer at the court of the Duke of Montechiaro, compiled a catalog of some 40 entries, including 19 real nebulous objects, found with a simple Galilean refractor of magnification 20, and printed in Palermo in 1654.

Thanks to Fredi De Maria of the ORSA, Palermo, Italy, Hodierna's book "De Admirandi Coeli Caracteribus", which contains his observations of nebulous objects, can now be found online. The book and the images were made available by the Osservatorio Astronomico di Palermo. The present author is grateful to Fredi for mailing him a copy of the article by Serio et.al.. This allowed me to revise this page appropriately.

Hodierna classified his objects according to what he thought they were resolvable into stars; he believed that all nebulous objects were actually cluster, which was a common view at that time, since Galilei had resolved the Milky Way, and e.g. the Praesepe cluster M44. The scheme was:

As for most early classifications, Hodierna's is of historical interest only and not related to physical object types.

Hodierna's observations include an independent rediscovery of the Andromeda Nebula (M31), and at least 9 (probably 10) own true discoveries, as listed by Kenneth Glyn Jones: M6, M36, M37, M38, M41, M47, NGC 2362, NGC 6231, NGC 6530 (the cluster associated with the Lagoon Nebula M8) and (possibly) NGC 2451. Hodierna was also the first who made a still preserved drawing of the Orion Nebula M42, where he resolved 3 of the Trapezium stars.

A list of the objects described by Hodierna follows. It was taken from Serio's original article, corrected for the misprint of NGC 2445 for NGC 2451, and contains several more objects not given above: It lists an original rediscovery of Brocchi's Cluster, an original "discovery" or first description of the Alpha Persei Moving Cluster, the probable original discoveries of M34, M33, and NGC 752, as well as possible original discoveries of NGC 2169 and NGC 2175.


Ha. I.1        M45 (Pleiades)
Ha. I.2        Hyades (Mel 25)
Ha. I.3        Coma Berenices Star Cluster, Mel 111
Ha. I.4    !   Alpha Persei Moving Cluster, Mel 20
Ha. I.5        M42
Ha. I.6        Asterism including Lambda, Phi1 and Phi2 Orionis
Ha. I.7    !   NGC 6231
Ha. I.8        Asterism in "the Water of" Aquarius


Ha. II.1       M44 (Praesepe)
Ha. II.2       M7
Ha. II.3       NGC 869/884, h and Chi Persei
Ha. II.4   !   M6
Ha. II.5       Asterism of Nu1, Nu2 Sagittarii
Ha. II.6   !   NGC 6530 (associated with M8)
Ha. II.7   !   M36
Ha. II.7   !   M37
Ha. II.7   !   M38
Ha. II.8  (!)  "Al Sufi's Nebula", Brocchi's Cluster, Collinder 399
Ha. II.9       Asterism around 88 Herculis
Ha. II.10      Asterism in front of the head of Capricornus


Ha. III.1      Asterism in Coma Berenicis
Ha. III.2      Asterism in Coma Berenicis
Ha. III.3 (!)  M31     

Other Nebulae Listed in Text

Ha. IV.1   !   M47
Ha. IV.2   !   M41
Ha. IV.3       asterism including Nu1, Nu2, Pi Puppis
Ha. IV.4   !?  probably M33
Ha. IV.4   !?  probably NGC 752
Ha. IV.5       ? insufficient description
Ha. IV.6       ? insufficient description
Ha. IV.7       ? insufficient description
Ha. IV.8       non-existent nebulosity near Hyades
Ha. IV.9       non-existent nebulosity near Pleiades
Ha. IV.10  !?? NGC 2169 ?
Ha. IV.11  !?? NGC 2175 ?
Ha. IV.12  !?  probably M34 
Ha. IV.13      ? insufficient description
Ha. IV.14      ? insufficient description
Ha. IV.15      ? insufficient description

Nebulae Shown in Maps Only

Ha. V.1    !   NGC 2362
Ha. V.2    !?  NGC 2451 ? (misprinted 2445 in Serio's article)
Ha. V.3        Asterism including k1, k2 Velorum (near NGC 2671)
Ha. V.4        Asterism in Canis Maior including star HD 58535

Please email me pointers to any errors, clarifications and/or comments, as well as any further info you have.

  • More Deepsky Observing lists
  • History of the Discovery of the Deepsky Objects
  • Some other historical catalogs
    Hartmut Frommert (spider@seds.org)
    Christine Kronberg (smil@lrz.uni-muenchen.de)

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    Last Modification: 8 Feb 1998, 20:00 MET